Polyester resins are known in their uses are known in the art. Polyester resins are incorporated into coating compositions, as either a primary or additive resin, to participate in a cross-linking reaction with a cross-linking agent to form a film of the coating composition on a substrate upon application and cure.
It is known throughout the art that certain convention polyester resins are inadequate. More specifically, it is known that the inclusion of certain conventional polyester resins in coating compositions, especially in clearcoat coating compositions, sacrifices the overall integrity of the cured film. One critical physical property that is representative of the overall integrity of the cured film is flexibility as evaluated by cold gravelometer, i.e., chipping, testing. The flexibility of the cured film is particularly important as the substrate weathers and as the substrate is repeatedly exposed to harsh environmental conditions, such as exposure to stones, rocks, etc. It is also known that the cured films of clearcoat coating compositions, which incorporate certain conventional polyester resins, do not maintain acceptable appearance over time due to inadequate gloss retention.
In sum, the polyester resins of the prior art are characterized by one or more inadequacy, including those described above. Due to such inadequacies, it is desirable to provide a novel polyester resin that improves the flexibility and maintains the appearance of a cured film of a coating composition that incorporates the polyester resin. With the improved flexibility, the cured film produced by the coating composition which incorporates the polyester resin of the subject invention is more resilient to chip.